Application of microwave-assisted technology: a novel process to produce gold nanostars and their spectroscopy characterizations

Abstract

In this paper, we report a novel seed-mediated method for the preparation of gold nanostars using microwave irradiation. These gold nanostars are produced in different mixed solutions including anionic and zwitterionic surfactants, AgNO 3 and ascorbic acid as reducing agent at room temperature by seed-mediated method using microwave irradiation. Moreover, microwave irradiation plays an important role in mediating the branched growth of the resultant gold nanostars by inducing anisotropic growth on the surfaces of initially formed spherical gold nanoparticles. The gold nanostars are characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and x-ray powder diffraction. It is shown that the gold nanoparticles were formed with star shape (size ranging from 50 to over 100 nm with different branches and aspect ratios (ratio of branch length to width)) and facecentered-cubic (fcc) crystalline structure. Polyethylene glycol (PEG) is used as capping agent to prevent the aggregation of gold nanostars after removing mixed surfactants.

Bespoke nanostars: synthetic strategies, tactics, and uses of tailored branched gold nanoparticles

“…Ngo et al have recently shown that microwave-assisted, seed-based synthesis of monodisperse gold nanostars is not only possible, but also tuneable. 137 By altering the concentration of AA, CTAB, gold seed, and AgNO 3 , the researchers were able to take advantage of the microwave irradiation to yield rapidly formed, highly homogeneous nanostars. The use of both MW irradiation and ultrasound in the synthesis of template supported-metal nanoparticles has shown that changes in the duration, intensity, and any pulse-like flux rates of irradiation can alter the final morphology of the nanosystem.…”

Robust Joule-heating induced transmittance modulation of CNT-sheet-paraffin based smart window

“…Nevertheless, the main drawbacks of the ITO are the nonflexibility and limited source of indium for its production [3][4][5]. Various advanced materials which have been developing for the next generation of transparent heater devices are carbon-based materials [6,7], metal nanowire (MNW) networks [5,[8][9][10][11], metal nanomaterials [12][13][14] Significantly, the high uniformity of the aligned-CNT sheet has offered an excellent stable template, limiting the hot pots that have degraded performances of the transparent heater. Materials owning the thermal-induced transmittance change, such as organic phase change material (PCM) [22, 23], liquid crystal [24, 25], and hydrogel-derived liquid [26], have been used to combine with the transparent heater for the smart windows.…”